Cydia milleniana

Author: (Adamczewski, 1967)

Larch gall moth

Species Overview:

Adult: 13-18 mm wingspan; forewings grey-brown except interspaces between black-brown strigulae on apical two-thirds of costa, distal part of wing irrorate (tips of scales) with cream-white; discocellular area with a subquadrate or subtriangular brown-black patch; ocellus edged laterally with bluish plumbeous striae and marked with usually four, often wedge-shaped, dashes. Hindwing dark fuscous.
Egg: deposited singly; often on 2-3 year old shoots.
Larva: head brown; prothoracic plate brown, translucent, darker posteriorly; abdomen shining yellowish brown; pinacula brown, setae short, brownish; thoracic legs yellowish brown; anal plate brown.
Pupa: dark brown or black, shining; long and slender; in the larval habitation.

Taxonomic Description:

Male:

Cydia milleniana adult 1
Cydia milleniana adult 2
External characters: 14-18 mm wingspan. Forewing ground colour cream-white, overlaid with dark grey-brown except interspaces between black-brown strigulae on apical two-thirds of costa, some of the interspaces producing fractured bluish plumbeous striae, distal two-thirds of wing profusely irrorate (tips of scales) with cream-white, the irroration sometimes appearing yellow; basal and sub-basal fasciae obsolete; median fascia obsolescent, reduced to a short, moderately thick, outward-oblique black-brown streak from costa and a heavy, subquadrate or subtriangular brown mixed with black patch in discocellular area; ocellus well developed, edged laterally with bluish plumbeous striae and marked with usually four, often wedge-shaped, dashes, these sometimes fractured and partially contiguous; often a few black scales, sometimes forming dots, above ocellus and in subapical area; cilia concolorous with wing basally, otherwise grey, with a blackish brown sub-basal line weakened or interrupted subapically. Hindwing dark fuscous; cilia whitish grey, with a dark fuscous sub-basal line (Bradley et al., 1979).

male gen. Cydia milleniana
Genitalia: Ventral margin of neck of valva with small obtuse protuberance. Aedeagus open in distal lower side, upper wall sclerotized and falcate.

Female:

External characters: Similar to male.

female gen. Cydia milleniana
Genitalia: Anterior margin of lamella postvaginalis with small median processes, lamella postvaginalis slightly elongated laterally. Ductus bursae sclerotized. Corpus bursae with two small signa.

Variation:

The development of the median fascia, particularly the size and shape of the blackish patch in the discocellular area, and the black ocellar dashes show considerable variation.

Taxonomic note:

For many years, this species has been confused with Cydia zebeana. The biology of both species is almost similar, but larvae of the latter do not form resinous galls. Both species can easily be separated: the forewing of Cydia milleniana has one blackish spot anterior of the ocellus; in Cydia zebeana there are 4-5 blackish spots present.

Biology:

Due to the confusion of this species with Cydia zebeana, it is difficult to be sure about the data published on the biology of both species. Whitebread, 1975, and Booij and Diakonoff, 1983, explain that larvae of Cydia milleniana form galls, and the larvae of Cydia zebeana do not. According to Booij and Diakonoff, 1983, females deposit their eggs on 2 year old shoots, larvae take 2 years to develop and moths fly at least one week later than those of Cydia zebeana do, in June and July.
Bogensch├╝tz, 1991, gives the biology of a gall forming species which he calls Cydia zebeana, but the facts most likely concern Cydia milleniana as well. According to Bogensch├╝tz, adults fly in May and June. Eggs are deposited singly; axils of 3-year-old shoots are preferred oviposition sites. The young larvae penetrate into the bark immediately after hatching. The irregular feeding tunnel extends towards the sapwood and is coated with a fine web. The host tree reacts to the feeding by excretion of resin and formation of galls; the wood of the main branches, the branch axils and the base of the side branches expand in a knotty way. The gall attains the size of a pea in the first year of infestation and in the second year the size of a cherry. The faeces are excreted through a hole that has been gnawed through the gall wall. The larva pupates after the second hibernation in the gall. The pupal stage lasts about 4 weeks. Shortly before emergence of the adult, the pupa moves by rotational movements into the hole through which the excrements are disposed.

Host plants:

Larix spp.

Damage:

milleniana damage to Larix
Larvae can be found in larch plantations. They mine under the bark and cannot be detected, but gradually an elongate, rather uneven, resinous gall develops which is quite conspicuous.
Cydia milleniana only sporadically reaches harmful densities, but damage to young larch trees can be considerable at high densities of the larvae. Shoots may be desiccated by the presence of galls and may break by the action of the wind or the weight of snow. Bark wounds, caused by the feeding of the larvae, are penetration sites for spores of the larch cancer, Lachnellulla willkommii.

Distribution:

Europe to Russia and Korea.

Pheromone:

Pheromone unknown.

Attractantia:

E 8E 10-12Ac
Z 8Z 10-12Ac (Witzgall et al., 1996b)

Parasitoids:

(Record from Ivanovo region in Russia)
Macrocentrus sp.
Ascogaster sp.

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